package com.hmdp.service.impl;

import cn.hutool.core.bean.BeanUtil;
import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.hmdp.dto.Result;
import com.hmdp.entity.Shop;
import com.hmdp.mapper.ShopMapper;
import com.hmdp.service.IShopService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.CacheClient;
import com.hmdp.utils.RedisData;
import com.hmdp.utils.SystemConstants;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.geo.Distance;
import org.springframework.data.geo.GeoResult;
import org.springframework.data.geo.GeoResults;
import org.springframework.data.redis.connection.RedisGeoCommands;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.domain.geo.GeoReference;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.Resource;
import java.time.LocalDateTime;
import java.util.*;
import java.util.concurrent.Executor;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

import static com.hmdp.utils.RedisConstants.*;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
public class ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {

    @Resource
    private StringRedisTemplate stringRedisTemplate;
    @Resource
    private CacheClient cacheClient;

    @Override
    public Result queryById(Long id) {

        //缓存穿透
//        Shop shop = cacheClient.queryWithPassThrough(CACHE_SHOP_KEY, id,
//                Shop.class, this::getById, CACHE_SHOP_TTL, TimeUnit.MINUTES);
       // Shop shop = queryWithPassThrough(id);
        //互斥锁解决缓存击穿
        Shop shop = queryWithMutex(id);
        //Shop shop = queryWithLogicalExpire(id);
      /*  Shop shop = cacheClient.queryWithLogicalExpire(CACHE_SHOP_KEY, id,
                Shop.class, this::getById,20L,TimeUnit.SECONDS);

       */
        if (shop == null){
            return Result.fail("店铺不存在！");
        }
        return Result.ok(shop);
    }
    //创建线程池
    private static final ExecutorService CACHE_REBUILD_EXECUTOR =
            Executors.newFixedThreadPool(10);

    //使用逻辑过期的方法解决击穿问题
    public Shop queryWithLogicalExpire(Long id){
        //1.在redis查询是否存在
        String key = CACHE_SHOP_KEY + id;
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2.判断json是否是null
        if(StrUtil.isBlank(shopJson)){
            return null;
        }
        //3.把json对象反序列化为对象
        RedisData redisData = JSONUtil.toBean(shopJson, RedisData.class);
        Shop shop = JSONUtil.toBean((JSONObject) redisData.getData(), Shop.class);
        LocalDateTime expireTime = redisData.getExpireTime();
        //4.判断是否过期
        if(expireTime.isAfter(LocalDateTime.now())){
            return shop;
        }
        String lockKey = LOCK_SHOP_KEY + id;
        //获得锁
        boolean tryLock = tryLock(lockKey);
        //是否成功获得锁
        if(tryLock){
            //获取成功
            CACHE_REBUILD_EXECUTOR.submit(()->{
                try {
                    this.saveShop2Redis(id,20L);
                } catch (Exception e) {
                    e.printStackTrace();
                } finally {
                    unLock(lockKey);
                }
            });
        }
        //返回过期的商铺
        return shop;
    }

    //使用互斥锁来解决缓存击穿
    public Shop queryWithMutex(Long id){
        //1.在redis查询是否存在
        String key = CACHE_SHOP_KEY + id;
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2.存在则返回给前端
            if(StrUtil.isNotBlank(shopJson)){
            Shop shop = JSONUtil.toBean(shopJson, Shop.class);
            return shop;
        }
            //判断命中的是否是空值
        if(shopJson != null){
            return null;
        }
        String lockKey = LOCK_SHOP_KEY + id;
        Shop shop = null;
        try {
            //获得互斥锁
            boolean tryLock = tryLock(lockKey);
            if(!tryLock){
                //要是为获得成功，就休眠50ms
                Thread.sleep(50);
                //再次去请求
                return queryWithMutex(id);
            }
            //3.不存在，去数据库找
            shop = getById(id);
            //Thread.sleep(50);
            //4.数据库还是不存在则返回错误
            if(shop == null){
                stringRedisTemplate.opsForValue().set(key,"",CACHE_NULL_TTL, TimeUnit.MINUTES);
                return null;
            }
            //5.存在返回数据到redis
            stringRedisTemplate.opsForValue().set(key,JSONUtil.toJsonStr(shop),CACHE_SHOP_TTL,TimeUnit.MINUTES);
        } catch (InterruptedException e) {
           throw new RuntimeException(e);
        }finally {
            //释放互斥锁
            unLock(lockKey);
        }

        return shop;
    }

    //解决缓存穿透
    public Shop queryWithPassThrough(Long id){
        //1.在redis查询是否存在
        String key = CACHE_SHOP_KEY + id;
        String shopJson = stringRedisTemplate.opsForValue().get(key);
        //2.存在则返回给前端
        if(StrUtil.isNotBlank(shopJson)){
            Shop shop = JSONUtil.toBean(shopJson, Shop.class);
            return shop;
        }
        if(shopJson != null){
            return null;
        }
        //3.不存在，去数据库找
        Shop shop = getById(id);
        //4.数据库还是不存在则返回错误
        if(shop == null){
            stringRedisTemplate.opsForValue().set(key,"",CACHE_NULL_TTL, TimeUnit.MINUTES);
            return null;
        }
        //5.存在返回数据到redis
        stringRedisTemplate.opsForValue().set(key,JSONUtil.toJsonStr(shop));
        return shop;
    }



    private boolean tryLock(String key){
        Boolean flag = stringRedisTemplate.opsForValue()
                .setIfAbsent(key, "1", 10, TimeUnit.SECONDS);
        return BooleanUtil.isTrue(flag);
    }
    private boolean unLock(String key){
        Boolean flag = stringRedisTemplate.delete(key);
        return BooleanUtil.isTrue(flag);
    }
    public void saveShop2Redis(Long id,Long expireSeconds) throws InterruptedException {
        //查询店铺信息
        Shop shop = getById(id);
        //Thread.sleep(200);
        //封装逻辑过期时间
        RedisData redisData = new RedisData();
        redisData.setData(shop);
        redisData.setExpireTime(LocalDateTime.now().plusMinutes(expireSeconds));
        //写入redis
        stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY + id,JSONUtil.toJsonStr(redisData));
    }


    @Override
    @Transactional
    public Result update(Shop shop) {
        Long id = shop.getId();
        if(id == null){
            return Result.fail("店铺id不能为空");
        }
        //更新数据库
        updateById(shop);
        //删除缓存
        stringRedisTemplate.delete(CACHE_SHOP_KEY + id);
        return Result.ok();
    }

    /**
     * 附近商家的排序
     * 按照
     * @param typeId
     * @param current
     * @param x
     * @param y
     * @return
     */
    @Override
    public Result queryShopByType(Integer typeId, Integer current, Double x, Double y) {
        //判断是否要根据坐标查询
        if(x == null || y == null){
            // 根据类型分页查询
            Page<Shop> page = query()
                    .eq("type_id", typeId)
                    .page(new Page<>(current, SystemConstants.DEFAULT_PAGE_SIZE));
            // 返回数据
            return Result.ok(page.getRecords());
        }
        //计算分页参数
        int from  = (current - 1) * SystemConstants.DEFAULT_PAGE_SIZE;
        int end = current * SystemConstants.DEFAULT_PAGE_SIZE;
        //查询redis，按照距离排序，分页，结果shopId distance
        String key = SHOP_GEO_KEY + typeId;
        GeoResults<RedisGeoCommands.GeoLocation<String>> results =
                stringRedisTemplate.opsForGeo().search(key,
                GeoReference.fromCoordinate(x, y), new Distance(5000),
                RedisGeoCommands.GeoSearchCommandArgs.newGeoSearchArgs().includeDistance().limit(end));
        //解析出id
        if(results == null){
            return Result.ok(Collections.emptyList());
        }
        List<GeoResult<RedisGeoCommands.GeoLocation<String>>> list =
                 results.getContent();
        if(list.size()<=from){
            return Result.ok(Collections.emptyList());
        }
        //截取from -> end部分
        List<Long> ids = new ArrayList<>(list().size());
        Map<String, Distance> distanceMap = new HashMap<>(list.size());
        list.stream().skip(from).forEach(result -> {
            //获取店铺
            String name = result.getContent().getName();
            ids.add(Long.valueOf(name));
            //获取距离
            Distance distance = result.getDistance();
            distanceMap.put(name,distance);
        });
        //根据id查询shop
        String idStr = StrUtil.join(",", ids);
        List<Shop> shops = query().in("id", ids).last("ORDER BY FIELD(id," + idStr + ")").list();
        for (Shop shop : shops) {
            shop.setDistance(distanceMap.get(shop.getId().toString()).getValue());
        }
        return Result.ok(shops);
    }
}
